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Why The Radeon Gallium3D Performance Is Down

12-23-2011, 09:30 AM

Phoronix: Why The Radeon Gallium3D Performance Is Down

After yesterday's article about the Grinch that stole the Radeon Gallium3D performance, here's three offending commits since Mesa 7.10 that are causing the open-source Radeon Gallium3D driver to run slower than it should.

Comment

It looks like it was expected to see a 0-15% performance boost, but because GEM_WAIT was disabled, it ended up becoming a performance regression..
Disabing GEM_WAIT is probably temporary, so it's probably nothing to really worry about.

On a side note, the Gallium drivers have in the past needed more CPU usage to hit the higher framerates than the Catalyst drivers did.. So fixes like this that reduce overhead gets me all excited.

Comment

chrisr, it is reverted in this branch, which I will push soon:
git://people.freedesktop.org/~mareko/mesa radeon-perf-fix
It fixes the performance regression in Nexuiz and hopefully even the bug you reported.

Sidicas, the performance improvement is unrelated to the regression in r300g. The regression is caused by a commit that's merely a cleanup.

Michael, thanks for doing this. The commit "winsys/radeon: move GEM domains out of the drivers into winsys" will be reverted, fixing Nexuiz.
The commit "r300g: implement fences using dummy relocations" won't be reverted. It properly implements glFinish(), which is used by openarena to eliminate the input lag. It's important for playability of the game.